[Picus]

Horse power ratings from manufacturers are almost always to the crank. Most of them use the new SAE standard so they're *reasonably* reliable. The real variable is drive train loss. I think the generally agreed on number is 15%. 15% of 505 ~75hp, so the Z06 should have ~425 to the wheels. I believe most dyno's of stock Z06's are in that range. Of course that's not true for all cars, but some manufacturers are very conservative with their hp ratings.